/**
    * Logback: the reliable, generic, fast and flexible logging framework.
    * Copyright (C) 1999-2011, QOS.ch. All rights reserved.
    *
    * This program and the accompanying materials are dual-licensed under
    * either the terms of the Eclipse Public License v1.0 as published by
    * the Eclipse Foundation
    *
    *   or (per the licensee's choosing)
   *
   * under the terms of the GNU Lesser General Public License version 2.1
   * as published by the Free Software Foundation.
   */
  package ch.qos.logback.classic.pattern;
  
  import java.util.Iterator;
  import java.util.Map;
  import java.util.Set;
  
  import ch.qos.logback.classic.spi.ILoggingEvent;
  
  public class MDCConverter extends ClassicConverter {
  
    String key;
    private static final String EMPTY_STRING = "";
  
    public MDCConverter() {
    }
  
    @Override
    public void start() {
      key = getFirstOption();
      super.start();
    }
  
    @Override
    public void stop() {
      key = null;
      super.stop();
    }
  
    @Override
    public String convert(ILoggingEvent event) {
      Map<String, String> mdcPropertyMap = event.getMDCPropertyMap();
  
      if (mdcPropertyMap == null) {
        return EMPTY_STRING;
      }
  
      if (key == null) {
        // if no key is specified, return all the
        // values present in the MDC, separated with a single space.
        StringBuilder buf = new StringBuilder();
        Set<String> keys = mdcPropertyMap.keySet();
        Iterator it = keys.iterator();
        String tmpKey;
        String tmpValue;
        while (it.hasNext()) {
          tmpKey = (String)it.next();
          tmpValue = (String)mdcPropertyMap.get(tmpKey);
          //format: {testeKey=testValue, testKey2=testValue2}
          buf.append(tmpKey).append('=').append(tmpValue);
          if (it.hasNext()) {
            buf.append(", ");
          }
        }
        return buf.toString();
      }
  
      String value = event.getMDCPropertyMap().get(key);
      if (value != null) {
        return value;
      } else {
        return EMPTY_STRING;
      }
    }
  }